If a rail car has a cylindrical tank with a covered dome, how is it classified?

• A. Nonpressure tank
• B. Pressure tank
• C. Cryogenic tank
• D. Dedicated car

Answer: (B)

A rail car with a cylindrical tank that features a covered dome is classified as a pressure tank because the design indicates that it is built to handle higher pressures compared to a non-pressure tank. Pressure tanks are specifically engineered to contain liquids or gases that are stored at pressures above atmospheric pressure, ensuring that they can safely manage the stresses that come from the contents they hold.

The presence of a covered dome also suggests that the design includes features that manage pressure, as this dome can accommodate the expansion of gases or liquids within the tank, which is essential for maintaining safety and integrity under operational conditions.

In contrast, non-pressure tanks do not have the structural integrity to handle pressurized contents and are typically used for materials that can be stored safely at atmospheric pressures. Cryogenic tanks are specifically designed to hold materials at extremely low temperatures, and dedicated cars are typically specialized rail cars designed for particular types of cargo or use cases.